WATER MAY 2015
84
Technical Papers
Europe and the US have begun accepting,
directly into their digesters, high-strength
organic waste streams from industry,
agriculture and municipalities in order
to co-digest with sewage sludge. This
provides additional bioenergy generation
that offsets a large proportion of the
whole WWTP energy use.
In Europe, and to a lesser extent the
US, supportive bioenergy and waste
management policy is known to have
helped the uptake of AD as a technology.
So what are the policies overseas? Is
current Australian policy doing its best to
promote the use of AD technology? And
do WWTPs need strong policy support or
can AD be utilised without it? This paper
investigates the current use and state of
AD policy in Australia and how Australia’s
AD policy compares to benchmark nations.
In doing so, this paper demonstrates the
opportunities and barriers that face a
WWTP looking to use or expand AD,
with or without policy support.
SUMMARY OF AD
IMPLEMENTATION
AND POLICY: AUSTRALIA
AND ABROAD
BIOENERGY INCENTIVES
As shown in Figure 1, the implementation
of AD in Australia is far lower than in
other nations. The lack of adequate
government incentives for AD bioenergy
exported to the grid is most likely the
key reason for the poor uptake of AD,
as once onsite energy needs are met the
incentive to produce additional energy is
low. AD bioenergy does not qualify for a
feed-in-tariff (FiT) in all states in Australia,
with the exception of Victoria, where
systems smaller than 100kW capacity
are eligible and receive $0.062/kWh
(as of 1 January 2015).
AD bioenergy is eligible for large-scale
generation certificates (LGC) under the
Renewable Energy Target (RET) policy,
where plants received on average in
2013 $0.038/kWh. Small-to-medium sized
AD plants (less than 1MW generation
capacity) that look to export the majority
of their bioenergy are disadvantaged by
the RET, because costs associated with
connecting and staying connected to
the electricity grid will exceed revenue
from LGC and energy sales. This is due
to a combination of both high costs
to access and supply to the grid, and
LGC prices not being high enough.
The bioenergy incentives in Australia,
therefore, fail to build on the potential
contribution that small-to-medium sized
AD plants producing bioenergy can
make. This is contrary to the European
and US approach, where small-to-medium
capacity AD installations receive higher
FiTs as incentive to export bioenergy.
In Germany and the UK, AD reactors
that have a capacity less than 500kW
receive a higher FiT than those with
greater capacity, (BMU, 2007). In the US,
although only being applied in a handful
of states, FiTs are also favourable for
small-to-medium sized AD plants.
For medium-to-large AD, like that
in WWTPs, the lack of incentives for
exporting bioenergy to the grid in
Australia is not typically a concern.
Bioenergy in these plants is generated and
used on-site, offsetting heat and electricity
use in the wider wastewater treatment
process. Additionally, large agricultural
and industrial based AD reactors at
abattoirs, piggeries and some dairies, for
example, offset their own onsite energy
use apportioned to rendering, rearing and
milking processes, respectively. The use
of bioenergy onsite ensures the highest
value for the product as it offsets the need
to buy energy from retailers. Furthermore,
bioenergy used onsite in this manner is
still eligible for LGCs without the need
to connect to the grid.
RENEWABLE ENERGY AND
CLIMATE CHANGE POLICY
The dissolution of bipartisan support for
the Renewable Energy Target (RET) in
2014 as well as no agreed pathway on
a carbon tax, a GHG emission trading
scheme or an emission reduction fund, is
a prime example of the changing nature
of renewable energy policy in Australia.
The lack of a long-term stable renewable
energy policy has resulted in significant
market uncertainty with only $40 million
being invested in renewable energy in
the first half of 2014, compared to $2.7
billion in the full year prior (Sharpe,
2014). Feedstock supply security, funding
mechanisms and market demand for
bio-products (including bioenergy) are
intrinsically tied to government policy.
Decision makers interested in AD
have repeatedly called for a consistent
approach to waste management and
renewable energy, but to date this
has not been forthcoming. Places like
Europe and many states in the US, where
long-term renewable energy policy has
enjoyed stability and bipartisan support,
provide examples of consistent, secure
and long-term policy. Denmark is a chief
example for Australia as it has witnessed
stable long-term and ambitious
renewable energy policy, despite being
a net-energy exporter from oil and gas
reserves (IEA, 2011).
THE ROLE OF BIOSOLIDS
Biosolids regulation for the benefit
of human health and environmental
protection was the initial driver of AD
at WWTPs and continues to be crucial.
Australian biosolids policy is similar
in scope to the overseas jurisdictions
studied, where re-use is encouraged
but with caveats on heavy metal
concentrations, pathogen removal
and land application rates. To treat
and reuse biosolids in compliance with
these standards is expensive. In 2012,
$315 million was spent on biosolids
management by WWTPs in Australia
(Pollution Solutions and Design, 2012).
Unfortunately, policy mechanisms and
market conditions do not adequately
reflect the value of reclaiming crucial
components found within biosolids
products including carbon, phosphorous
and ammonia, or the potential for
biosolids to offset CO2 emissions
from avoided synthetic fertiliser
use. Policy also does not reflect the
benefit land-applied biosolids provides
by sequestering carbon in soil and
significantly improving soil quality
(Lal, 2005; Spargo et al., 2008).
The Carbon Farming Initiative (CFI)
offers a framework whereby biosolids
could be valued for offsetting emissions
and carbon sequestration by earning
carbon credits, although to date, despite
industry calls for its inclusion as a CFI
methodology, biosolids treatment
and land application has yet to qualify
as a methodology for the scheme.
Policy support to struvite formation
technologies that use AD supernatant
would assist in helping WWTPs balance
biosolids management budgets, too.
Biosolids policy in Europe and the US is
much the same as in Australia, with little
support to help treat and stablise the
sludge for higher beneficial use.
WASTE MANAGEMENT
While solid waste management policy
may not seem pertinent to WWTP AD
installations treating solely sludge, the
practice of co-digesting municipal and
commercial organic waste (biowaste) is
well established overseas. In Denmark,
Germany, the UK and in parts of the
US, strong solid waste management
policies have helped position WWTPs
as alternative treatment facilities for
biowaste. This has enabled WWTPs
BIOSOLIDS